Ported plenum, runners = won't stay running
Thread Starter
Instructor
Joined: May 2011
Posts: 103
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Ported plenum, runners = won't stay running
I had to do some work on my engine, so I decided to port and siamese the plenum and enlarge and siamese the runners. I got the engine to start but it will only run for a few seconds and it wants to idle high ( around 2200 RPM's). Is it possible that maybe the engine is getting to much air and not enough fuel, or am I missing something all together. 
I checked the fuel related fuses and they are good, and there are no vacuum leaks. 
Any help appreciated,
Mike
I checked the fuel related fuses and they are good, and there are no vacuum leaks. Any help appreciated,
Mike
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
If your engine wants to idle at 2000 RPM....it more than likely IS a vacuum leak. Check all your hoses....including the large one to the brake booster (often overlooked). Then you can try using a small piece of hose as a scope and move one end along all gasket surfaces to see if you can hear the sucking air sound. Are you sure that you have the runners sealed to the intake and the plemum?
Did you make any adjustments to the TB? Did you remove the TPS, if so, check to see if it is operating correctly...rotate the TB arm to open the butterfly and watch to see if the small arm on the TPS is moving or is it perhaps stuck.
Did you make any adjustments to the TB? Did you remove the TPS, if so, check to see if it is operating correctly...rotate the TB arm to open the butterfly and watch to see if the small arm on the TPS is moving or is it perhaps stuck.
Thread Starter
Instructor
Joined: May 2011
Posts: 103
Likes: 2
If I disconnect the MAF sensor, the engine will start and run, but it runs a little rough and of course the service engine soon light comes on. I checked all my bolts for my intake and vacuum lines and I don't hear any leaks. Also when I give it gas, it seems like it does not drop back down to idle as quickly as it used to. I did not remove the TPS or adjust the TB and the TPS seems to be working fine.
Last edited by 87vettevert; Jun 18, 2011 at 04:11 PM. Reason: addition
Melting Slicks
Joined: Sep 2010
Posts: 2,422
Likes: 202
clear your codes... use propane around your plenum... or use a vacuum gauge get a reading
porting all components on the TPI system to death... will not cause high idle.... has to be a loose area or leak... check all hoses....
porting all components on the TPI system to death... will not cause high idle.... has to be a loose area or leak... check all hoses....
Thread Starter
Instructor
Joined: May 2011
Posts: 103
Likes: 2
It ended up being the gasket between the TB and plenum; one of the corners at the bottom was folded over. :o It is amazing what kind of effect that can have on an engine.
Thanks to everyone for their help and thoughts
Mike
Thanks to everyone for their help and thoughts
Mike
